Investigation of PAHs, nitrated PAHs and oxygenated PAHs in PM10 urban aerosols. A comprehensive data analysis

Polycyclic aromatic compounds (PACs) in particulate matter contribute considerably to the health risk of air pollution. As such, we have optimized a method to determine the levels of polycyclic aromatic hydrocarbons, especially nitrated and oxygenated polycyclic aromatic hydrocarbons, in samples of PM₁₀ particulate matter using microwave-assisted extraction (MAE) and gas chromatography coupled to a triple quadrupole mass spectrometer (GC-MS/MS). The proposed method was applied to the analysis of real samples collected in the urban area of Ciudad Real (Spain) during one year. The median total concentrations of eighteen PAHs (∑PAHs) and seven OPAHs (∑OPAHs) were 0.54 and 0.23 ng m^-3, respectively, with the corresponding value for NPAH (∑NPAHs) being 0.03 ng m^-3 (only detected in 40% of samples). A clear seasonal trend was observed, with higher levels in the cold season and lower in the warm season for ∑PAHs. The same effect was observed for ∑OPAHs, which exhibited a median concentration of 0.72 ng m^-3 in the cold season and 0.10 ng m^-3 in the warm season, and for ∑NPAH, which exhibited a median of 0.04 ng m^-3 in the cold season but were not detected in the warm season. Molecular diagnostic ratios and PCA (principal component analysis) showed a predominantly traffic origin for PACs. The sources of PAHs also depend on meteorological conditions and/or atmospheric reactions, as confirmed by means of statistical analysis. The ∑OPAH/∑PAH and ∑NPAH/∑PAH ratios were higher in the cold season than the warm season, thus suggesting that PAH derivatives originated from primary combustion emission sources together with their parent PAHs. The concentration range found for benzo(a)pyrene was 0.006-0.542 ng m^-3, which is below the threshold value of 1 ng m^-3 established in European legislation as the annual average value. The lifetime lung risk from inhalation of PM₁₀-bound PACs was estimated to be six cancer cases per million people using the World Health Organization method.

Simultaneous biotreatment of Polycyclic Aromatic Hydrocarbons and dyes in a one-step bioreaction by an acclimated Pseudomonas strain

A Pseudomonas stutzeri strain acclimated to the presence of neoteric contaminants has been proposed for simultaneously remediating an effluent polluted with Polycyclic Aromatic Hydrocarbons and a diazo dye. The pollutants chemical nature imposed a strict control of both the medium composition and the operating conditions. pH, temperature and agitation rates of 7.0, 37.5 and 146 rpm, respectively, led to optimum levels of contaminant removal (higher than 60%) after RSM optimization. The validity of these conditions was checked at flask and bioreactor scale and the kinetics of the biotreatment was elucidated. The simulation of this one-step process applied at larger scale for the remediation of a 200,000 m(3)/year-effluent from a leather factory was compared with a conventional two-steps option. Great reductions in treatment times and in investment and manufacturing costs were concluded, proving the promising potential of the proposed process.